Laser mirror mount and window protection assembly

ABSTRACT

A laser is described which includes optical mirror mounting structure providing stable support for the optical mirrors and yet enabling precise and reproducible angular reorientation of the same with respect to the optical axis of the lasing tube. The mounting structure for each of such mirrors includes a pair of generally parallel, rectangular plates, one of which is rigidly associated with the lasing tube and the other one of which is a mount for the mirror. Such plates are adjustably connected together adjacent three corresponding corners to provide orthogonal adjustment of one with respect to the other. Each connection at a corner includes a tuning bolt which is threadably received within one of the plates and bears against the other. It also includes a leaf spring rigidly secured between such plates to provide a compressive force on its associated tuning bolt. Each of such leaf springs is formed by a pair of leaf portions respectively secured to an associated one of the plates and extending generally transversely with respect to the direction of movement of the tuning bolt, which portions defines an expandable joint in the leaf spring enabling the same to lengthen to compensate for changes in the distance between the plates caused by the tuning bolt. A tubular cover is provided at each end of the lasing tube extending therebetween and the optical mirror associated with such end. Each of such tubular covers includes a ball joint permitting angular orientation of the mirror mounting structure with respect to the envelope and, hence, the optical axis.

United States Patent [191 Mohler 1 Feb. 4, 1975 LASER MIRROR MOUNT ANDWINDOW PROTECTION ASSEMBLY Galen E. Mohler, Mountain View, Calif.

[73] Assignee: Lexel Corporation, Palo Alto, Calif.

[22] Filed: Aug. 29, 1973 [2]] Appl. N0.: 392,614

[75] Inventor:

Primary Examiner-Ronald L. Wibert Assistant Examiner-Michael J. TokarAttorney, Agent, or Firm-C. Michael Zimmerman [57] ABSTRACT A laser isdescribed which includes optical mirror mounting structure providingstable support for the optical mirrors and yet enabling precise andreproducible angular reorientation of the same with respect to theoptical axis of the lasing tube. The mounting structure for each of suchmirrors includes a pair of generally parallel, rectangular plates, oneof which is rigidly associated with the lasing tube and the other one ofwhich is a mount for the mirror. Such plates are adjustably connectedtogether adjacent three corresponding corners to provide orthogonaladjustment of one with respect to the other. Each connection at a cornerincludes a tuning bolt which is threadably received within one of theplates and bears against the other. It also includes a leaf springrigidly secured between such plates to provide a compressive force onits associated tuning bolt. Each of such leaf springs is formed by apair of leaf portions respectively secured to an associated one of theplates and extending generally transversely with respect to thedirection of movement of the tuning bolt, which portions defines anexpandable joint in the leaf spring enabling the same to lengthen tocompensate for changes in the distance between the plates caused by thetuning bolt. A tubular cover is provided at each end of the lasing tubeextending therebetween and the optical mirror associated with such end.Each of such tubular covers includes a ball joint permitting angularorientation of the mirror mounting structure with respect to theenvelope and, hence, the optical axis.

11 Claims, 8 Drawing Figures PATEHTEU i 75 SHEEI 10F 2 LASER MIRRORMOUNT AND w mnow PROTECTION ASSEMBLY BACKGROUND OF THE INVENTION Thepresent invention relates to mounting structure for optical instrumentsand, more particularly. to such an instrument which enables the positionof an optical device with respect to an optical axis to be accuratelyadjusted. The invention more specifically relates to a laser whichincludes a simple mounting structure pro viding precise and stableangular reorientation of the laser end mirrors with respect to theoptical axis of the lasing tube.

It is important in most optical instrumentation that optical devices ofone sort or another, such as lenses, mirrors, prisms, etc., be preciselypositionable with respect to an optical axis. For example, properoperation of a laser depends on precise and stable angular alignment ofthe optical reflectors (mirrors) at the opposite ends of the lasingmedium envelope. Such alignment is necessary to assure that therequisite number of passes of the optical radiation through the lasingmedium are effected for laser oscillation. Moreover, it is desirablethat such alignment be precisely and reproducibly ad'- justable toenable differing wavelength outputs and optimization of the outputpower.

Much effort and time has been spent by those in the art in attempts toarrive at a satisfactory mirror mounting structure for lasers providingthe desired stable positioning while allowing precise angularreorientation. It is now generally accepted that such a mountingmechanism preferably provides independent rotational movement of themirror about at least two perpendicular axes to assure that any desiredangular setting can be achieved. However, the apparatuses which havebeen designed in the past to provide such adjustments have not beenentirely satisfactory. They are, in general, relatively complicated anddo not provide the precise and stable positioning desired. For example,some of such devices have included coil springs extending between themirror mount and a reference structure. Such springs generally.interfere with the stableness of any given mirror setting and thesensitivity with which changes can be made. Prior mounting structuresoften have also included tieing structure of one sort or another betweenthe mirror mount and the reference structure to maintain mirror settingsrigid, which tieing structure has interfered with truly independentmovement about the perpendicular axes.

SUMMARY OF THE INVENTION The present invention is a mounting structurefor an optical instrument such as a laser, which provides a highlystable support for an' optical device and adjustment of the positioningof such device with both a high degree of accuracy and sensitivity. Thestructure of the invention satisfies-such functions while yet beingsimple and not requiring the use of components, such as coil springs andtieing structures, which interfere with optimum operation thereof. Inits basic aspects, the mounting structure includes, as is usual for sucha structure, a reference member positioned at a predetermined locationrelative to an optical axis of the instrument, and a mount for theoptical device whose position is to be adjusted with respect to suchoptical axis. The connecting means between the mount and the referencememher providing the adjustment includes a separator, such as a tuningbolt, which extends between the reference member and the mount formaintaining the same spaced apart. The length of such separator along apath extending directly between the reference member and the mount isselectively variable to enable the distance between such referencemember and the mount at the location of such reference member to bechanged.

The connecting means further includes a leaf spring which has itsopposite ends secured to the reference member and the mount and is intension therebetween to resiliently urge the same toward one another bymaintaining a compressive force onthe separator. As a particularlysalient feature of the instant invention, the leaf spring includes anexpansion and contraction joint between its ends which enables the sameto lengthen or shorten to compensate for changes in the distance betweenthe reference member and the mount. Most desirably, the joint of theleaf spring includes a reentrant portion which extends transversely withrespect to the path along which the length of the separator isselectively variable. Joint expansion and contraction is thus obtainedby changes in the included angle of the reentrant portion. Theorientation of the reentrant portion transversely with respect to theseparator path reduces or, as in the case with the preferred embodiment,eliminates any adverse affect on the rigidity of the connection betweenthe mount and reference member caused by the expandable joint of theleaf spring.

The mounting structure is particularly designed to be included in alaser as an adjustable mounting structure for an optical reflectorpositioned across the optical axis along which energy emanating from thelasable medium passes in order to intercept such energy for reflection.When included as part of a laser, such mounting structure most desirablyincludes three orthogonally located separators and associated leafsprings which includes an expansion and contraction joint in order toenable independent orthogonal rotation as desired.

As another salient feature of the instant invention, it includes atubular cover which extends between the laser envelope enclosing lasingmedium and such mounting structure, which cover allows the mountingstructure to be used to angularly reorient the reflector whilemaintaining it isolated from the ambient atmosphere exteriorly of thelaser envelope. Such cover has its opposite ends respectively secured tothe lasing medium envelope and such mounting structure, and includes atubular ball joint along its length which responds to such angularreorientation. Most desirably, such tubular cover is provided by a pairof coaxial tubes which join one another with the ends of one of suchtubes at such joint being received withiin the end of the other tubethereat. The ball joint then includes a rigid ball surface on one of thejoining ends, mating with a deformable elastic portion on the other ofthe joining ends. This arrangement will provide the desired ball jointconnection while maintaining integrity of a seal thereat. Moreover, itwill permit axial movement of the tubes relative to one another withoutthe integrity of such seal being broken.

The invention includes other features and advantages which will bedescribed or will become apparent from the following more detaileddescription of the preferred embodiments.

3 BRIEF DESCRIPTION OF THE DRAWINGS With reference to the accompanyingtwo sheets of drawing:

FIG. 1 is a generally schematic, elevation view of a laser incorporatinga preferred embodiment of the present invention;

FIG. 2 is an enlarged, elevation view of the laser mirror mountingstructure viewed from the plane indicated by the lines 2-2 in FIG. 1;

FIG. 3 is a further enlarged, partial sectional view taken on the planeindicated by the lines 3-3 in FIG. 2, and illustrating a preferredembodiment of the connecting means of the invention;

FIG. 4 is a view similar to FIG. 3 showing the connecting means at adifferent position of adjustment;

FIG. 5 is an end elevation view similar to FIG. 2 of a laser mirrormounting structure incorporating another preferred embodiment of theinvention;

FIG. 6 is a partial end view of the mounting structure of FIG. 5providing details of the connecting means thereof;

FIG. 7 is an enlarged elevation view of the tubular cover component ofthe invention; and

FIG. 8 is a sectional view of the tubular cover taken on a planeindicated by the lines 8-8 in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to theaccompanying drawings, FIG. 1 is an overall view ofa laser incorporatingthe present invention. Such laser includes an elongated envelope or tube11 which encloses a lasable medium, i.e., quantum resonant particles,such as an ionized noble gas, e.g., argon, at a pressure of about 1torr. As is conventional, means (not shown), such as an electrode and apower source, are provided for initiating an electrical discharge in thelasable medium. The result will be that optical radiation will bepropagated along the axis 12 of the tube 11, which axis is referred toherein as the optical axis. Such radiation passes through windows at theopposite ends of the tube 11 and is reflected by optical reflectors ormirrors 13 at such ends back and forth through the tube a sufficientnumber of times to sustain laser oscillation. Transmission of opticalradiation'through one or both of the reflectors, as represented at 14,constitutes the coherent light radiation output of the laser.

As mentioned previously, it is necessary to provide a mounting structurefor each of the mirrors which will support the same quite stably at anygiven position and yet allow highly sensitive and reproducible changesto be made in the angular orientation of such mirrors with respect tothe optical axis 12. Mounting structures, referred to generally by thereference numerals l6 and 17, are respectively included at the oppositeends of the laser for such purpose. Each of such structures includes areference member in the form of a rectangular plate 18 which ispositioned at a predetermined location relative to the optical axis 12.In this connection, the opposite plates 18 are joined via three rods 19which are secured therebetween adjacent corresponding corners of suchplates. Rods 19 are, in turn, supported via spaced apart verticaluprights 21 which project upwardly from a base 22. The uprights 21 alsoact as supports for laser tube 11. It is the supporting structure madeup of the rods 19, the uprights 21, andthe base 22 which support thereference plates 18 at predetermined locations with respect to the tube11, and, hence, the optical axis 12.

Each of the mounting structures 16 and 17 further includes a mount forits associated optical reflector 13. That is, as illustrated, each ofthe optical reflectors is mounted at the front wall of a cylindricalextension 23 projecting coaxially with the optical axis 12 from arectangular mount plate 24.

Each of the plates 24 is positioned parallel and adjacent to itsassociated reference plate 18, and means are provided for connectingeach of the mounts to its associated reference member for adjustment ofthe position of such mount with respect to such reference member and,hence, with respect to the optical axis 12. Such connecting meansincludes three separate connections 26, 27 and 28 which are spaced fromone another and from the optical axis 12. More particularly, as is bestseen from FIG. 2, the three connections provide connection between theassociated reference and mounting plates at three corresponding cornersthereof. Each of the connecting means enables adjustment at its locationof the distance between the reference and mounting plates. Furthermore,the locations of such connecting means are so related that straightlines drawn respectively from the connections 26 and 28 to theconnection 27 will intersect one another generally at a right angle.Thus, such connections cooperate to provide independent rotationalmovement of the mounting plate and, hence, the optical reflector aboutperpendicular axes to enable desired orthogonal adjustments.

Each of the connecting means includes two components, a separator whichextends between the reference and mount plates to maintain the samespaced apart at the location of the respective connecting means, and aleaf spring which is in tension between the reference and mount platesto resiliently urge the plates toward one another by maintaining acompressive force on the separator. The position adjustment at each ofthe connections is obtained by varying the length of the separator alonga path which extends directly between the reference and mount plates.The connecting means 26 through 28 are generally the same, and theirdetails will be described with reference to connecting means 26. Moreparticularly, as shown in FIGS. 2 and 3, the separator is in the form ofa tuning bolt 29 which extends threadably through the mount plate 24 andterminates in a bearing end 31 which abuts or bears against the facingsurface of the reference plate 18. The leaf spring of each of theconnections is generally referred to by the reference numeral 32 and hasits opposite ends respectively secured to the reference plate 18 andmount plate 24. That is, the ends 33 and 34 of the spring are positionedrespectively against the upper end surfaces of the mount and referenceplates and are rigidly secured thereto by bolts 36.

The utilization of a leaf spring to provide the compressive force on theseparator tuning bolts has the advantage of providing such compressiveforce while at the same time preventing parallel displacement orparallel rotation of the plates with respect to one another. As aparticularly salient feature of the instant invention, the spring 32includes an expansion and contraction joint between its ends whichenables the same to length and shorten to compensate for any change inthe distance between the reference and mount plates without affectingthe rigidity with which such spring prevents parallel displacementbetween such plates. More particularly, the spring 32 includes areentrant portion 37 extending transversely of the direction along whichthe tuning bolt changes the separation between such plates. Thistransverse relationship of the reentrant portion to the direction ofmovement of the tuning bolt provides the desired expandable jointwithout the necessity of there being any parallel displacement orrotation between the plates when they are separated. As illustrated, theleaf spring is formed by a pair of leaf portions 38 and 39 whichrespectively provide the ends 33 and 34 which are secured to themounting and reference plates. The remainder of each of the leafportions, i.e., that portion of each which is positioned between themount and reference plates, extends generally transversely of the bolt29. Such leaf portions terminate in second ends which are rigidlysecured together by rivets 41. Each of the leaf spring portions 38 and39 are made of a spring steel, and the rivets 41 tend to maintain thesame back-to-back, i.e., abutting one another for the full length whichextends between the mounting plates. However, because of the securanceof the upper ends of each to the respective plates 18 and 24, suchportions are forced apart. It is the resistance to such separation bythe leaf spring portions which places the leaf spring in tension betweenthe reference and mount plates and thereby provides the compressiveforce on that portion of the tuning bolt extending between the plates.

FIGS. 3 and 4 illustrate the reference and mount plates with twodifferent separation distances. The reaction of the spring to suchdiffering separations is readily apparent from a comparison of suchfigures. That is, the greater length of spring which must be provided inthe direction of the separation for a greater separation distance asillustrated in FIG. 4, is provided by a corresponding reduction in thelength of such spring transversely to such direction. In other words,

the joined ends of the leaf portions move upward as viewed in thedrawing toward the other ends of such leaf portions when the plates areseparated further apart. This transverse compensation for the expansionenables such expansion to take place without there being any paralleldisplacement of the plates because of the securance of the leaf springtherebetween.

. With reference again to FIGS. 1 and 2, it will be recognized thatrotation of tuning bolt 29 of the connection 26 will result in rotationof the mount plate 24 relative to the reference plate I8 about an axiswhich passes between the tuning bolts of the connections 27 and 28. Bythe same token, rotation of the tuning bolt of the connecting means 28will result in rotation of the mount plate about an axis which passesbetween the tuning bolts of connections 26 and 27. Thus, the desiredorthogonal rotations can be effected merely by rotating the tuning boltsof the connections 26 and 28 to vary the distance between such plates attheir respective locations. To facilitate manual rotation of the tuningbolts of such connections 26 and 28, each is provided with a knurledtuning knob 42.

Adjustment of the distance between the two plates at the connection 27by rotation of the tuning bolt thereat will reorient the plane definedby the two axes about which the connecting means 26 and 28 providerotation. Since such an adjustment generally is made only infrequently,the tuning bolt of such connection is provided with a hexagonal socket43 for engagement by a suitable tool to effect such rotation, ratherthan a tuning knob.

It will be appreciated that in order to obtain reproducibility andsensitivity, the connections between the mounting and reference platesmust be maintained precisely within close tolerances at all times. Thatis, play in the connections cannot be tolerated. The design of the leafspring assures that it will not contribute to any play, assuming, ofcourse, that its ends are rigidly secured to the respective plates.There is, however, the possibility of some play in any threadedengagement of parts, such as between the engaging threads of the tuningbolts and the bores in the mounting plate through which such boltsextend. To eliminate such play, means are provided for adjusting thelateral compressive pressure to which each of the bolts is subjected inthe bore by the mounting plate. That is, as can best be seen from FIG.2, each of the bores through which one of the bolts extends is providedwith a slot which projects from the edge of the mounting platetransversely through and in communication with such bore. An adjustmentscrew 46 connects opposite sides of each of the slots for drawing thesame toward one another. It will be appreciated that rotation of theadjustment screw will thus effect a change in the dimension across thebore transversely of the slot. Thus, such screw can be rotated toincrease the pressure provided by the bore on the bolt which extendstherethrough. Such pressure is thus adjustable to compensate for anyfree play between the threads of the bolt and those of the bore.

It will be noted from FIG. 2 that the leaf spring of each of theconnections is positioned closely adjacent the point at which the tuningbolt of the connection passes between the reference and mount plates.This close positioning will assure that the compressive force providedby the spring will apply only a minimum of torque at the lcoation atwhich the separator is positioned. It is recognized, however, that insome optical uses of the mounting structure of the invention, even suchlow torque can have an effect on the accuracy and sensitivity ofadjustment. FIGS. 5 and 6 illustrate an alternate embodiment of themounting structure which eliminates the effect of such torque. Withreference to such figures, it will be seen that the leaf spring 47 ofeach of the connections 48, 49 and 50 of such mounting structure ispositioned on opposite sides of the path of its associated tuning bolt51 to balance any torque applied to such tuning bolt by the springcompressive force. That is, each of the leaf portions 52 and 53 of eachspring 47 is provided with an axially located slot 54 through which itsassociated tuning bolt 51 extends. The resulting pair of separated earson the spring are rigidly connected via bolts 56 to the plates toprovide the securance of the opposite ends of the spring therebetween.This construction results in any compressive force provided by thespring on one side of the tuning bolt 51 to be balanced by an equal andopposite torque due to such compressive force on the opposite side ofthe bolt.

The embodiment of FIGS. 5 and 6 is in all other respects substantiallythe same as the embodiment of FIGS. 1 and 2. For this reason, like partsare referred to by like reference numerals.

It is most desirable that the path of optical radiation in the laser, aswell as all optical components thereof, be maintained free ofcontamination. The lasing tube 11 is sealed, with'the result thatcontamination interiorly thereof is no problem, assuming that nocontamination is present when the tube atmosphere is initially placedtherein. Protection against contamination and dirt should also beprovided for the optical components of the laser exteriorly of the tubeand the path of radiation along the optical axis exteriorly of suchtube. The means for providing such'protection, however, must be meanswhich does not hinder accurate adjustment of the angular orientation ofthe optical reflectors with respect to the lasing tube. As anothersalient feature of the instant invention, it includes means whichprovides protection against contamination without in any way affectingsuch adjustment.

More particularly, with reference to FIGS. 1, 7 and 8, a tubular coveris provided at opposite ends of the envelope 11 enclosing the path foroptical energy along the optical axis between such envelope and each ofthe optical reflectors 13. To this end, each tubular envelope 61includes a threaded end 62 which is threadably received within a bore inthe mount plate with which it is associated. Such end will thereforeprovide communication between the cover and the tubular extension 23which otherwise encloses the optical reflector 13 mounting on suchmounting plate. The other end of each tubular cover includes a collar 63which, as is best illustrated in FIGS. 7 and 8, circumscribes the endofthe lasing tube with which it is associated and is sealed thereon by anO-ring seal 64. Such arrangement will result in the transmission window66 at the end of the envelope being contained within the tubularstructure.

As a particularly salient feature of the tubular cover, it includes atubular ball joint between its ends which allows angular orientation ofthe mount plate with respect to the envelope and, hence, with respect tothe optical axis. More particularly, the tubular cover 61 is provided bya pair of coaxial tubes 67 and 68 joining one another at adjacent endsand having their opposite ends defining the tubular cover ends 62 and 63which are respectively secured to the mount plate and to the envelope 11about the window 64. The end of the tube 68 is received within thejoining end of the tube 67. Such tube 68 is made of a rigid material,such as a metal, and includes a circumferential ball surface 69projecting peripherally therefrom at said end. Such ball surface therebyprovides a rigid ball for the ball joint. The tube 67, on the otherhand, is of a deformable elastic material, such as of Teflon, with aradius less than the radius of the peripheral ball surface 69. Theresult is that the end of such tube which surrounds the ball will bedeformed thereby and, because of its elasticity, grip the same toprovide a seal.

It will be recognized that the tubular ball joint provided by the matingends ofthe tubes 67 and 68 will enable angular movement of one withrespect to the other at such joint as illustrated in FIG. 7. Just asimportantly,

the construction of such ball joint enables the tubes to move axiallywith respect to one another. That is, because the ball cavity is notrigid, but rather is provided by the deformable elastic tube 67, axialmovement of the tubes at such ball joint is permitted. Thus, themounting structure to which the tube 68 is secured is completely freefor movement, including movement axially along the optical axis.Adjustment of the optical reflector is therefore not hindered by thetubular cover.

Most desirably, the tube 67 is selectively releasable from the lasablemedium envelope II. To this end, the

end of tube 67 adjacent the lasing medium envelope includes anintermediate collar 71 which is threadably received within the collar63. As can be seen from FIG. 8, rotation of such collar 71 with respectto the collar 63 will result in release of the tube from around theenvelope 11. Moreover. because the tube 67 is elastic, such tube isretractable from the window 66 by being telescopically slid over thetube 68. This enables access to the window for the purpose of cleaningand the like.

While the invention. has been described in connection with preferredembodiments thereof, it will be appreciated by those skilled in the artthat various changes and modifications can be made without departingfrom its spriit.

It is therefore intended that the coverage afforded applicant be limitedonly by the claims and their equivalents.

I claim:

1. In a laser which includes an an elongated envelope enclosing alasable medium and having a window at an end thereof for the passagetherethrough of optical energyalong an optical axis, an opticalreflector positioned transversely of said optical axis exteriorly ofsaid envelope to intercept optical radiation emanating from said window,mounting structure for said optical reflector which allows the angularorientation of the same to be accurately adjusted relative to saidoptical axis, and a tubular cover enclosing the path for optical energyalong said optical axis between said envelope and said reflector, saidcover having opposite ends respectively secured to said envelope aboutsaid window and to said mounting structure and including a tubular balljoint along its length permitting changes in the angular orientation ofsaid mounting structure with respect to said envelope and, hence, saidoptical axis, said tubular cover including a pair of coaxial tubesjoining one another atadjacent ends and having their opposite endsrespectively secured to said envelope about said window and to saidmounting structure, one of said joining ends of one of said tubes beingreceived within the end of the other end of said tubes thereat, and saidball joint including a rigid ball surface on one of said joining endsmating with a deformable elastic portion on the other of said joiningends, said deformable elastic portion of said other joining endextending axially of said tube beyond said rigid ball surface wherebyaxial movement of said ball in said other end is accommodated.

2. The laser of claim 1 wherein said one of said tubes which is securedto said envelope about said window is selectively releasable therefrom,and said tube is telescopically slidable with respect to the other oneof said tubes to enable retraction thereof from said window tofacilitate access to the latter.

3. In a laser which includes an elongated envelope enclosing a lasablemedium and having a window at an end thereof for the passagetherethrough of optical energy along an optical axis; an opticalreflector positioned transversely of said optical axis exteriorly ofsaid envelope to intercept optical energy emanating from said window;and mounting structure for said optical reflector enabling adjustment ofthe angular orientation thereof with respect to said optical axis, whichmounting structure includes a reference member positioned at apredetermined location relative to said optical axis, a mount for saidreflector, and means connecting said mount to said reference member foradjustment of the angular orientation of said mount with re spect tosaid reference member, said connecting means including:

A. a first connection between said reference member and said mountspaced from said optical axis;

B. a second connection between said mount and said reference member at asecond location spaced from the location of said first connection;

C. said first connection having:

1. a separator which extends between said reference member and saidmount at said first location for maintaining the same spaced apartthereat, the length of said separator along a path extending directlybetween said reference member and said mount at said first locationbeing selectively variable; and

2. a leaf spring having opposite ends respectively secured to saidreference member and said mount and being in tension therebetween toresiliently urge said reference member and said mount toward one anotherat the location of said first connection by maintaining a compressiveforce on said separator, said leaf spring being characterized byincluding an expansion and contraction joint under tension between saidopposite ends enabling said spring to lengthen and shorten to compensatefor changes in the distance between said reference member and said mountwhile maintaining a compressive force on said separator;

D. said expansion and contraction joint being free of said secondconnection for changes in the distance between said reference member andsaid mount at the location of said first connection independently ofdistance changes therebetween at the location of said second connection;

whereby selective variation ofthe length of said separator of said firstconnection along said path changes the angular orientation between saidreference member and said mount whenever said second connectionmaintains the distance therebetween constant at its location.

4. The laser of claim 3 wherein said expansion and contraction joint ofsaid leaf spring includes a reentrant portion of said spring whichextends transversely with respect to the path along which the length ofsaid separator is selectively variable.

5. The laser of claim 4 wherein said reentrant portion of said leafspring is formed by a pair of leaf portions, each of which has a firstend respectively secured to an associated one of said reference memberand said mount and extends from said first end transversely with respectto the path along which the length of said separator is selectivelyvariable to a second end rigidly secured to the second end of the otherone of said leaf portions.

6. The laser of claim 3 wherein said connecting means includes a thirdconnection between said reference member and said mount spaced from thelocations of said first and second connections and positioned at a thirdlocation at which straight lines drawn thereto from each of thelocations of said first and second connections will intersect oneanother generally at a right angle, and wherein said second connectionincludes a second separator extending between said reference member andsaid mount for maintaining the same spaced apart at said secondlocation, the length of said second separator along a path extendingdirectly between said reference member and said mount at said secondlocation being selectively variable, and a second leaf spring at saidsecond location having opposite ends respectively secured to saidreference member and said mount and being in tension therebetween toresiliently urge said reference member and said mount toward one anotherat said second location by maintaining a compressive force on saidsecond separator, said second leaf spring including an expansion andcontraction joint under tension between said opposite ends enabling saidsecond leaf spring to lengthen and shorten to compensate for changes inthe distance be tween said reference member and said mount at thelocation of said second connection while maintaining a compressive forceon said second separator, said expansion and contraction joint of saidsecond leaf spring being free of both of said first and thirdconnections for changes in the distance between said reference memberand said mount at the location of said second connection independentlyof distance changes therebetween at the locations of said first andthird locations, whereby selective variation of the length of saidsecond separator along said path changes the angular orientation betweensaid reference member and said mount whenever said first and thirdconnections maintain the distance therebetween constant at theirrespective locations.

7. The laser of claim 6 wherein said third connection includes a thirdseparator extending between said reference member and said mount at saidthird location for maintaining the same spaced apart thereat, the lengthof said third separator along a path extending directly between saidreference member and said mount at said third location being selectivelyvariable, and a third leaf spring at said third location having oppositeends respectively secured to said reference member and said mount andbeing in tension therebetween to resiliently urge said reference memberand said mount toward one another at said third location by maintaininga compressive force on said third separator, said third leaf springincluding an expansion and contraction joint under tension between saidopposite ends enabling said third leaf spring to lengthen and shorten tocompensate for changes in the distance between said reference member andsaid mount at said third location while maintaining a compressive forceon said third separator, said expansion and contraction joint of saidthird leaf spring being free of both said first and second connectionsfor changes in the distance between said reference member and said mountat the location of said third connection independently of distancechanges therebetween at the locations of said first and secondlocations, whereby selective variation of the length of said separatorof said third connection along said path changes the angular orientationbetween said reference member and said mount whenever both said firstand second connections maintain the distance therebetween constant attheir respective locations.

8. The laser of claim 3 wherein said separator is a tuning bolt whichextends threadably through one of said reference member and said mountand terminates in an end abutting against the other one of saidreference member and said mount, the length of said bolt extendingdirectly between said reference member and said mount being selectivelyvariable by rotating the same with respect to the one thereof throughwhich it extends to thereby advance or retract the same.

9. The laser of claim 8 wherein means are included for adjusting thelateral compressive pressure to which said bolt is subjected by said oneof said reference member and said mount through which it extends.

10. The laser of claim 9 wherein said means for adjusting the pressureto which said bolt is subjected by said one of said reference member andmount through which it extends includes a slot extending transversely toand communicating with the bore through which said bolt extends, and anadjustment screw threadably connecting opposite sides of said slot fordrawing said opposite sides toward one another to increase said saidoptical axis.

1. In a laser which includes an an elongated envelope enclosing alasable medium and having a window at an end thereof for the passagetherethrough of optical energy along an optical axis, an opticalreflector positioned transversely of said optical axis exteriorly ofsaid envelope to intercept optical radiation emanating from said window,mounting structure for said optical reflector which allows the angularorientation of the same to be accurately adjusted relative to saidoptical axis, and a tubular cover enclosing the path for optical energyalong said optical axis between said envelope and said reflector, saidcover having opposite ends respectively secured to said envelope aboutsaid window and to said mounting structure and including a tubular balljoint along its length permitting changes in the angular orientation ofsaid mounting structure with respect to said envelope and, hence, saidoptical axis, said tubular cover including a pair of coaxial tubesjoining one another at adjacent ends and having their opposite endsrespectively secured to said envelope about said window and to saidmounting structure, one of said joining ends of one of said tubes beingreceived within the end of the other end of said tubes thereat, and saidball joint including a rigid ball surface on one of said joining endsmating with a deformable elastic portion on the other of said joiningends, said deformable elastic portion of said other joining endextending axially of said tube beyond said rigid ball surface wherebyaxial movement of said ball in said other end is accommodated.
 2. Thelaser of claim 1 wherein said one of said tubes which is secured to saidenvelope about said window is selectively releasable therefrom, and saidtube is telescopically slidable with respect to the other one of saidtubes to enable retraction thereof from said window to facilitate accessto the latter.
 2. a leaf spring having opposite ends respectivelysecured to said reference member and said mount and being in tensiontherebetween to resiliently urge said reference member and said mounttoward one another at the location of said first connection bymaintaining a compressive force on said separator, said leaf springbeing characterized by including an expansion and contraction jointunder tension between said opposite ends enabling said spring tolengthen and shorten to compensate for changes in the distance betweensaid reference member and said mount while maintaining a compressiveforce on said separator; D. said expansion and contraction joint beingfree of said second connection for changes in the distance between saidreference member and said mount at the location of said first connectionindependently of distance changes therebetween at the location of saidsecond connection; whereby selective variation of the length of saidseparator of said first connection along said path changes the angularorientation between said reference member and said mount whenever saidsecond connection maintains the distance therebetween constant at itslocation.
 3. In a laser which includes an elongated envelope enclosing alasable medium and having a window at an end thereof for the passagetherethrough of optical energy along an optical axis; an opticalreflector positioned transversely of said optical axis exteriorly ofsaid envelope to intercept optical energy emanating from said window;and mounting structure for said optical reflector enabling adjustment ofthe angular orientation thereof with respect to said optical axis, whichmounting structure includes a reference member positioned at apredetermined location relative to said optical axis, a mount for saidreflector, and means connecting said mount to said reference member foradjustment of the angular orientation of said mount with respect to saidreference member, said connecting means including: A. a first connectionbetween said reference member and said mount spaced from said opticalaxis; B. a second connection between said mount and said referencemember at a second location spaced from the location of said firstconnection; C. said first connection having:
 4. The laser of claim 3wherein said expansion and contraction joint of said leaf springincludes a reentrant portion of said spring which extends transverselywith respect to the path along which the length of said separator isselectively variable.
 5. The laser of claim 4 wherein said reentrantportion of said leaf spring is formed by a pair of leaf portions, eachof which has a first end respectively secured to an associated one ofsaid reference member and said mount and extends from said first endtransversely with respect to the path along which the length of saidseparator is selectively variable to a second end rigidly secured to thesecond end of the other one of said leaf portions.
 6. The laser of claim3 wherein said connecting means includes a third connection between saidreference member and said mount spaced from the locations of said firstand second connections and positioned at a third location at whichstraight lines drawn thereto from each of the locations of said firstand second connections will intersect one another generally at a rightangle, and wherein said second connection includes a second separatorextending between said reference member and said mount for maintainingthe same spaced apart at said second location, the length of said secondseparator along a path extending directly between said reference memberand said mount at said second location being selectively variable, and asecond leaf spring at said second location having opposite endsrespectively secured to said reference member and said mount and beingin tension therebetween to resiliently urge said reference member andsaid mount toward one another at said second location by maintaining acompressive force on said second separator, said second leaf springincluding an expansion and contraction joint under tension between saidopposite ends enabling said second leaf spring to lengthen and shortento compensate for changes in the distance between said reference memberand said mount at the location of said second connection whilemaintaining a compressive force on said second separator, said expansionand contraction joint of said second leaf spring being free of both ofsaid first and third connections for changes in the distance betweensaid reference member and said mount at the location of said secondconnection independently of distance changes therebetween at thelocations of said first and third locations, whereby selective variationof the length of said second separator along said path changes theangular orientation between said reference member and said mountwhenever said first and third connections maintain the distancetherebetween constant at their respective locations.
 7. The laser ofclaim 6 wherein said third connection includes a third separatorextending between said reference member and said mount at said thirdlocation for maintaining the same spaced apart thereat, the length ofsaid third separator along a path extending directly between saidreference member and said mount at said third location being selectivelyvariable, and a third leaf spring at said third location having oppositeends respectively secured to said reference member and said mount andbeing in tension therebetween to resiliently urge said reference memberand said mount toward one another at said third location by maintaininga compressive force on said third separator, said third leaf springincluding an expansion and contraction joint under tension between saidopposite ends enabling said third leaf spring to lengthen and shorten tocompensate for changes in the distance between said reference member andsaid mount at said third location while maintaining a compressive forceon said third separator, said expansion and contraction joint of saidthird leaf spring being free of both said first and second connectionsfor changes in the distance between said reference member and said mountat the location of said third connection independently of distancechanges therebetween at the locations of said first and secondlocations, whereby selective variation of the length of said separatorof said third connection along said path changes the angular orientationbetween said reference member and said mount whenever both said firstand seCond connections maintain the distance therebetween constant attheir respective locations.
 8. The laser of claim 3 wherein saidseparator is a tuning bolt which extends threadably through one of saidreference member and said mount and terminates in an end abuttingagainst the other one of said reference member and said mount, thelength of said bolt extending directly between said reference member andsaid mount being selectively variable by rotating the same with respectto the one thereof through which it extends to thereby advance orretract the same.
 9. The laser of claim 8 wherein means are included foradjusting the lateral compressive pressure to which said bolt issubjected by said one of said reference member and said mount throughwhich it extends.
 10. The laser of claim 9 wherein said means foradjusting the pressure to which said bolt is subjected by said one ofsaid reference member and mount through which it extends includes a slotextending transversely to and communicating with the bore through whichsaid bolt extends, and an adjustment screw threadably connectingopposite sides of said slot for drawing said opposite sides toward oneanother to increase said pressure.
 11. The laser of claim 3 furtherincluding a tubular cover enclosing the path for optical energy alongsaid optical axis between said envelope and said reflector, said coverhaving opposite ends respectively secured to said envelope about saidwindow and to said mounting structure and including a tubular ball jointalong its length allowing said angular orientation of said mountingstructure with respect to said envelope and, hence, said optical axis.